Despite having different underlying concepts, agile methods and User-Centered Design aim ultimately at producing high quality software. Aiming at providing better understanding on how usability evaluation is addressed within agile environments, we carried out multiple-case studies in two large IT companies. On the one hand, our studies corroborate the literature with regards to the execution of usability inspection evaluations on lightweight prototypes, taking advantage of the iterative nature of Agile. On the other hand, we observed contrary to the literature that this iterative nature of Agile has not facilitated the execution of user testing sessions. Furthermore, we noticed that it is extremely difficult to perform traditional user testing sessions due to the tight schedules inherent to Agile. Finally, we describe a set of practices that can help improve specific artifacts in different stages of an agile process in order to successfully evaluate software product usability.